These kinds of instruments are known and afford minimally invasive treatment of, for example, adenomas or tumors of the prostate. The actual treatment proceeds by means of a special treatment instrument within the instrument itself, for example by a laser-, HF- or microwave-probe. This allows the treatment to be observed through examination optics, namely an endoscope. To ensure a clear view, it is expedient to develop the instrument as a suction-flushing instrument, so that liquid flushing agent is pumped in front of the viewing area of the distal endoscope window, and the liquid is then removed via openings through the instrument.
Because particles such as mucous membrane parts, blood coagulum and the like should be drawn off together with the flushing agent, it is necessary that the suction canal(s) be of at least sufficiently large dimensions for the liquids to flow back. Moreover, the cross-section of the draining canal must correspond to the cross-section of the supply canal or could even be slightly bigger, in order to avoid in any case an excess pressure through bubbles. These demands, however, conflict with the demands for a small caliber instrumentation.
From DE-GM 84 16 392 a uretero-renoscope is known having an oval outer shaft and a smaller inner shaft forming an empty space in between for the draining off of liquids. To be sure, because of its oval outer shaft, this instrument already ensures a comparatively large and very usable inner cross-section while having a small perimeter. However, the cross-sections of the canals for supplying and draining of the flushing agent are rather small. It is also felt to be disadvantageous that, upon insertion of a laser probe, this can only be introduced insufficiently in the area of the laser fiber. A reduction of the shaft cross-section in this area, however, would make it impossible to introduce the probe head, which has a larger diameter than the remaining part of the probe. Finally, the instrument's structure makes it difficult to clean.
To be sure, there are already known some resectoscopes that are more easily cleaned. However, many feature a plurality of instrument parts, generally three separable parts, and have therefore proven to be difficult to handle.